Yes, anyone in the world — instructor, student, or other — is permitted to use all items in our collection.
Because these textbooks are openly licensed, anyone may make changes to the textbook as long as the original author is given credit. For example, instructors can make changes to these books to fit what is needed in the classroom.
For more information, see the Adaptation Guide – 2nd Edition and Not Just Another Textbook in the Self-Publishing Guide.